Silver halide emulsions sensitized with alkylene oxide polymers



United States Patent 3,210,191 SILVER HALIDE EMULSIONS SENSETIZED WITH ALKYLENE OXKDE POLYMERS Jozef Frans Willerns, Wilrijk, Antwerp, Rohrecht Julius Thiers, Brasschaat, Antwerp, and Joseph Louis De Muuck, Beveren, Waas, Belgium, assignors to Gevaert Photo-Iroducten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Filed Nov. 3, 1961, Ser. No. 149,850 Claims priority, application Netherlands, Nov. 4, 1960, 257,624 3 Claims. (Cl. 96107) The present invention relates to an improved photographic material, and more particularly to silver halide emulsion layers with enhanced developability and general light-sensitivity.

It is known that the general sensitivity of photographic emulsions which can already optimally be sensitized throughout the whole range of the spectrum by means of the so-called chemical sensitizers, such as sulphur sensitizers, can be still further increased if polyglycols are added to these photographic elements (British specifications Nos. 548,019 and 600,058).

It is also known that the same increase of sensitivity can be obtained by incorporating into the photographic material alkylene oxide polymers obtained by polymerzing alkylene oxide in the presence of hexitol ring dehydration products, aliphatic alcohols, aliphatic acids, amines, amides and phenols (British specifications Nos. 592,676, 748,745 and 748,750).

It is further known that these polyglycols and alkylene oxide polymers should possess a molecular weight of at least 400 and, in order to obtain a noticeable effect it is in practice necessary to use compounds which possess a molecular weight of 1500 to 2000 and more.

Contrary to the other known methods for increasing the sensitivity of silver halide emulsions such as those wherein the chemical sensitizers increase the inherent sensitivity and these wherein the cyanine dyes increase the spectral absorption, it appears that the final sensitivity of the silver halide emulsion layers wherein these compounds are incorporated is higher since these compounds exert a favourable influence on the development of these silver halide layers by means of the usual developers. These compounds can thus be considered as development accelerators.

It is, however, also known that these compounds, irrespective of the fact that they can be used as a component in more sensitive silver halide layers, make these layers less suitable for storage and specially for storage at elevated temperatures and relative humidities, since these compounds considerably increase the fog. It was further found that these compounds, when added to a photo graphic element for obtaining more sensitive silver halide emulsion layers, impair the image-tone of the developed silver obtained and give rise to brown and reddish-brown images.

It has now been found that the developability of lightsensitive emulsions can favourably be influenced by adding to one or more emulsion layers or other layers, belonging to the photographic material, compounds obtained by the polycondensation of low molecular alkylene oxide derivatives, which of themselves have little activity with aldehydes and polyamines.

In applying this new method it was noticed that in most cases higher sensitivities can be obtained with these compounds than with the known polyalkylene compounds. It was further found that these new compounds give rise ice to less fog during storage and that they do not influence the image tone of the developed silver.

These new compounds as such are ter-condensates of polyoxy alkylene derivatives with molecular weight less than 1500, polyamino compounds and aldehydes, so that a complicated structure and a complicated partition of the structure units is to be expected. In using tri-functional compounds such as melamine, crosslinking is not excluded here.

In the preparation of these tier-condensates formaldehyde or compounds which are able to split off formaldehyde such as p-formaldehyde, trioxymethylene or hexamethylene tetramine are preferred as aldehyde compounds. Also other aliphatic aldehydes such as acetaldehyde and croton aldehyde, and as aromatic aldehyde e.g. benzaldehyde can be used; as heterocyclic aldehyde e.g. furfural can be employed. It is evident that also mixtures of aldehydes may be used in preparing the above mentioned ter-condensates.

Besides aliphatic amines such as ethylene diamine also aromatic or heterocyclic amines such as melamine (2,4,6- triamino-1,3,5-triazine), diamino methyltriazine, guanazole and others, as well as mixtures of polyamino compounds are considered as dior polyamino compounds.

The proportion, in which the three above identified starting substances for the condensation are used, may

vary within large limits and depend on the desired properties of the condensation product. It is, however, de sired to choose the proportions in such a way that a Watersoluble condensation product is obtained.

An example of a favourable proportion of reagents is egg. 1 mol of polyamine, 3 to 6 mols of aldehyde and 2 mols of lower polyoxy alkylene compounds.

The condensation is realized by mixing the three basic products and heating under stirring to about C. When the mixture forms a homogeneous mass the temperature is raised to 150 C. and the formed water is distilled off. Sometimes it is desirable to eliminate more thoroughly the water split off during the condensation, by carrying out the reaction under reduced pressure some moments before stopping the heating.

By way of illustration some preparations are described hereinafter.

PREPARATION 1 for cooling. Finally 193 g. of a white waxy product are obtained.

PREPARATION 2 In a three-necked flask, provided with a stirrer, a thermometer and a condenser, 2.5 g. (0.2 mol) of 2,4- diamino-6-methyl-l,3,5-triazine are mixed with 9 g. (0.12 mol) of a 40% aqueous solution of formaldehyde and 40 g. (0.04 mol) of polyoxy ethylene glycol with molecular weight of 1,000 before heating. Whilst stirring this mixture is heated to 85 C. for 10 min. Then the temperature of the reaction mixture is raised to 130 C. in 4 h., while 7 cm. of water are distilled'ofl.

The residue is poured out into a flat cup for cooling. 35 g. of a white waxy product are obtained.

PREPARATION 3 In a three-necked flask, provided with a stirrer, a thermometer and a condenser, 3 g. (0.05 mol) of ethylene diamine are mixed with 15 g. (0.2 mol) of a 40% aqueous solution of formaldehyde and 100 g. (0.1 mol) of polyoxy ethylene glycol with molecular weight 1,000 before heating. Whilst stirring this mixture is heated to 85 C. for min. Then the temperature of the reaction mixture is raised to 130 C. in 4 h., while 10 cm. of Water are distilled off. The residue is poured out into a fiat dish for cooling. 102 g. of a light-brown waxy product are obtained.

The compounds according to the present invention may be added to the emulsions or they may be brought into intimate contact with the silver halide emulsion layers, either by dissolving them in water or in an aqueous mixture of organic solvents which do not disadvantageously influence the silver hailde emulsions and whereafter the solutions obtained is added to an emulsion or applied to an emulsion layer as a coating composition.

The compounds can be introduced into the emulsion at various stages during its preparation; for example, they may be incorporated as a separate addition, or mixed with one or more of the other ingredients used at the first precipitation of the silver halide grains, during the physical or chemical ripening process, or at some other point prior to coating the emulsion. Preferably, they are added after the chemical ripening and just before coating the emulsion.

The optimum amount of the compound to be added to the emulsion depends on the particular compound chosen, the nature of the colloid binding agent for the silver halide grains and the amount and kind of silver halide in the emulsion. In general, however, the compounds according to the invention are added in a quantity of 100 mg. to 10 g. per mol silver halide. If necessary, however, still other quantities of these compounds can be added which fall outside these limits.

The process of the present invention can be combined with a method for increasing the sensitivity of photographic material by incorporating therein small amounts of a sulphur-containing compound, such as allyl isothiocyanate, allyl thiourea and sodium thiosulphate, small amounts of reducing sensitizers such as the tin compounds described in Belgian specifications Nos. 493,464 and 568,- 687, the imino-aminomethane sulphinic acid compounds described in British specification No. 789,823 or small amounts of noble metal compounds such as of gold, platinum, palladium, iridium, ruthenium and rhodium. As a matter of fact, the new process is advantageously combined with the sensitizing action of compounds originally present in gelatin.

By application of the method according to the present invention stabilizing agents such as, for example, mercury compounds and the compounds claimed and referred to in the statement of prior art of Belgian specifications Nos. 571,916 and 571,917 may be added to the emulsion. It is also usual to sensitize and/ or to stabilize silver halide emulsions by incorporating therein cadmium salts or by carrying out their processing in the presence of cadmium salts. The compounds of the present invention can further be combinedwith oniurn compounds such as ammonium, sulphonium or phosphonium compounds. Still other ingredients such as anti-fogging agents, colour couplers, developing substances, hardening and wetting agents, can moreover and without deleteriously alfecting the emulsion, be added thereto in a manner known to those skilled in the art.

As a result of their property of conferring a better developability, the new compounds are effective in inc Hydroquin-one creasing the X-ray sensitivity and the general light-sensitivity of orthochromatic, panchromatic, and all special emulsions, as well as the ordinary non-spectrally sensitized ones. Thus, they can be added without or with optical sensing dyes but in the latter case not together with these dyes. They are also useful with a variety of emulsions, since a pronounced increase of speed is obtained in either negative or positive types of emulsions.

Although the method according to the present invention is especially appropriate for the treatment of gelatin silver halide emulsions, the invention is not limited to such colloid emulsions. Emulsions based on other waterpermeable colloids may also be treated according to the present invention. Among such colloids are e.g. to be mentioned: agar-agar, zein, collodion, water-soluble cellulose derivatives such as hydrolysed cellulose acetate; cellulose esters of hydroxycarboxylic acids, for example lactic or glycollic acid; alkali metal salts of cellulose esters of dicarboxylic acids such as phthalic acid; polyvinyl alcohol, and partially hydrolysed polyvinyl acetate and intcrpolymers of vinyl acetate with unsaturated compounds such as styrene and maleic acid, water-soluble polyvinyl acetals and other hydrophilic synthetic or natural resins or polymeric compounds.

The new developing accelerators may be used for sensitizing the known types of silver chloride, silver bromide, silver iodide emulsions and emulsions containing mix tures of these halides.

Furthermore, the methods as described in the above examples are not limited, as far as the quantity and the nature of the developing accelerator to be added or the moment of the addition are concerned. Indeed, for obtaining an optimum elfect, all particular techniques in the preparation of light-sensitive emulsions should be taken into account.

An advantage of this invention is the compatibility of the new developing accelerators with colour couplers and optical sensitizing dyes, which fact is of great importance for using the new developing accelerators to increase the general light-sensitivity of colour photographic material containing one or more light-sensitive layers.

A further advantage of the material according to the present invention resides in its simple application such as e.g. in the manufacture of light-sensitive materials for amateur and professional photography and cinematography, in graphic proceses and in scientific and industrial applications.

Hereinafter follow some examples which illustrate our present invention without limiting, however, the scope thereof.

Example I A washed coarsely grained gelatin silver iodobromide negative type of emulsion (average grain size 0.8a) wherein the silver halide consists of 94.5 mol percent silver bromide and 5.5 mol percent silver iodide is ripened at 45 C. After addition of a panchromatic sensitizing dye and other usual ingredients the emulsion is coated onto a suitable support (sample 1). Further samples were prepared by adding, prior to coating, to the same emulsion and per mol silver halide present the amounts of developing accelerators listed below. They are then treated as sample 1. After drying and exposure they are developed for 7 min. at 20 C. in a solution consisting of:

Water cm. 800 p-Methyl amino phenol sulphate Sodium sulphite (anhydrous) Borax Boric acid Potassium bromide Water up to 1000 cmfi.

6 Sensitometric results: such as 5-hydroxy-7-methyl-s-triazolo-(4,5a)-pyrimidine and of other usual ingredients, the emulsion is coated onto a suitable support (sample 1). Added developing Added Relative Further samples are prepared by adding to the same sample accelerator amount, Gamma FOE 5 emulsion, prior to Coating, and, per mol silver halide y present, the amounts of developing accelerators listed 1 P01 ow ethylene 100 0 43 O below. They are then treated as sample 1. After drying 1yco1with and exposure they are developed for 4 min. into a solution g ht 1 000 1a g g 82 3g 0. 1? 1 consisting of. 1b. .4 1 0. 0.

Comgound from 0.34 117 0.48 0.11 0 Water 800 9 p-Methylamrno phenol sulphate g 4 $12 1%; 8:22 8: Sodium sulphite (anhydrous) g 65 Hydroquinone g 10 5 Sodium carbonate (anhydrous) g 45 Potassium bromide g 5 Example 2 water up to 1000 cm. An emulsion sample is taken which is composed as in Sensitometric results: Example 1, while the development proceeds for 7 min. at C. in the following developer: 20 Added developing Added Relative Grams Sample accelerator amount, tsensJi- Gamma Fog g. 1v1 y p-Methylamlno phenol sulphate 10 Sodium sulphite (HDhYdI'Ol-IS) 7O 10g 3 7g 0 03 1 Compound from 1. 6 155 3. 86 O. 09 Potassium bromide preparation 1 Sodium carbonate (anhydrous) 5 Compounlfrogn 0.8 178 3.38 0.14

I Water P to 1000 08553525 11 8 178 3.74 0. 09

prepara ion Sensitometric results:

Afterdincubttion indai humid me 1111113 increase empera- Sample Added developing Added Relative Gamma Fog ture accelerator amount, g. sensitivity Relative Gamma Fog sensitivity 1 100 0. 58 0.13 100 0. 52 0.13 2 Compound from 3.4 108 0.71 0.15 105 0.60 0.18

preparation 1.

Example 3 We claim: l. A light-sensitive photographic material comprising ed as in i g i f 312 323: 5 fig z gfiiz g gg g min at a support and at least one gelatmo silver halide emulsion i followin dgvefo er layer containing an alkylene oxide polymer in an amount g p Grams between 100 mg. and 10 g. per mol of silver halide, said alkylene oxide polymer bein a water soluble product of 0.5 P go d ifi r r i ii l l h i e ti taili di 100 V the simultaneous condensation of a polyalkylene glycol H dro uingne y n 5 50 having a molecular weight of less than 1500 formaldehyde g gzg iz fii gg u 80 and an organic polyarnine having at least two amino Potassium bromide y u 2 groups, each with an active hydrogen atom thereon, said Citric acid 2 formaldehyde being present in an amount having a molar Wateru 616662;; ratio relative to the combined amounts of glycol and polyarnine of about 0.5:1 to 2:1. Sensrtometrrc results: 2. A light-sensitive photographic material comprising a support and at least one gelatino silver halide emulsion S 1 Add d d e p aggi s g v Gamma F0 layer containing an alkylene oxide polymer in an amount amp e am em or tivity g between 100 mg. and 10 g. per mol of silver halide, said alkylene oxide polymer being a water soluble product of 1 100 0.70 0.16 the simultaneous reaction of 2 mol of a polyalkylene 2 g gggg gg f 119 M9 17 glycol having a molecular weight less than 1500 and 3 to 3 tlo 3.4 1 6 mols of formaldehyde and 1 mol of an organic polyamine having at least two amino groups, each with an Example 4 active hydrogen atom thereon.

A washed coarsely grained gelatin silver iodobromide A hght-sensitlve P g p c material comprising emulsion wherein the silver halide consists of 98.2 mol a PP and atleast one l d hallde 51111151911 percent silver bromide and 1.8 mol percent silver iodide is layer, said emulsion layer being 1n intimate contact With ripened at 42 C. After addition of a stabilizing agent an alkylene oxide polymer wh1ch is a water-soluble prod- 7 55 not of the simultaneous reaction of a polyalkylene References Cited by the Examiner glycol having a molecular Weight of less than 1500, UNITED STATES PATENTS formaldehyde and an organic polyamine having at least 1 970 578 8/34 Schoener et al 260468 two amino groups, each with an active hydrogen atom 2:716:O62 8/55 Carroll et a1- thereon, said formaldehyde being present in an amount having a molar ration relative to the combined amounts of NORMAN TORCHIN, Primary Examine!- glycol and polyamine of about 0.5:1 to 2: 1. LOUISE P. QUAST, Examiner. 

1. A LIGHT-SENSITIVE PHTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND AT LEAST ONE GELATINO SILVER HALIDE EMULSION LAYER CONTAINING AN ALKYLENE OXIDE POLYMER IN AN AMOUNT BETWEEN 100 MG. AND 10 G. PER MOL OF SILVER HALIDE, SAID ALKYLENE OXIDE POLYMER BEING A WATER SOLUBLE PRODUCT OF THE SIMULTANEOUS CONDENSATION OF A POLYALKYLENE GLYCOL HAVING A MOLECULAR WEIGHT OF LESS THAN 1500 FORMALDEHYDE AND AN ORGANIC POLYAMINE HAVING AT LEAST TWO AMINO GROUPS, EACH WITH AN ACTIVE HYDROGEN ATOM THEREON, SAID FORMALDEHYDE BEING PRESENT IN AN AMOUNT HAVING A MOLAR RATIO RELATIVE TO THE COMBINED AMOUNTS OF GLYCOL AND POLYAMINE OF AOBUT 0.5:1 TO 2:1. 